In order to select the appropriate smoothing method,
a comparative analysis is made between mean filter
and median filter. On one hand, the main noise is
Gaussian noise in the image acquisition, while
median filter is not effective to Gaussian noise. On
the other hand, as shown in Table Ⅰ, it is concluded
that the larger template, the more time required; and
mean filter consumes more little time than median
filter. Considering these aspects, mean filter is
obviously superior to median filter in this system.